If you passed on this in theaters because you thought it was just another schlock horror movie, now's your chance to make up for the mistake. Mixing a sick sense of humor with a stream of cinema in-jokes, Popcorn is actually a subversive spoof of schlock horror movies itself included.
The action unfolds at an abandoned movie palace, where a group of film students is holding an all-night ''horror-thon,'' unaware that a disfigured psycho killer is lurking in the wings. The parallels with The Phantom of the Opera are nicely underplayed, though the plot is pretty much secondary to the elaborate movies-within-the-movie parodies of '50s grade Z thrillers. This Popcorn is as deliciously junky as the stuff in those microwave packs. B